Field of the Invention
The present invention relates generally to agricultural seeders that produce open furrows in the soil into which seeds are placed, and more particularly, to an improved sliding seed firmer and method of attaching and operating such firmer for use with seeders in securing seed-to-soil contact.
Description of the Prior Art
Agricultural planting methods continue to evolve in response to widespread adoption of “no-till” or “reduced-till” crop production techniques with greatly reduced dependence on tillage of the soil, and in which the next crop's seeds are often placed directly into the previous crop's stubble or crop residues. No-till or reduced-till seeding differs greatly from seeding into a tilled seedbed. The soil conditions for no-till seeding are typically wetter than those dried by tillage, due to the mulching effect of the crop residue remaining on the soil surface. No-till soils are also typically more structurally stable than tilled soils, as the soil particles are “aggregated” or held together by old roots, fungi, and other organic substances and molecular attractions binding the particles together.
The value of pressing newly planted seeds into the soil has likely been known since the dawn of agriculture, and in-furrow firming wheels were described and depicted at least as early as 1908 in Davis, U.S. Pat. No. 939,812. Some earlier “presser” wheels are taught by Patric et al., U.S. Pat. No. 404,108, issued in 1889, although these firming devices were relatively wide and further rearward than the device described in Davis '812, and essentially allowed (and relied upon) considerable loose soil to slough into the furrow ahead of the firming device, and are more in the vein of a modern ‘packer’ or ‘press’ wheel operating upon the soil surface and compressing all of the soil filled over the seed. The different methods and actions of such seed-firming devices on freshly formed furrows and planted seeds becomes still more important in no-till conditions due to the greater structure or resilience of no-till soils as compared to tilled soils, which renders pressing from the soil surface ineffective and damaging to the seed environment. Soils which are eroded or which have otherwise suffered degradation from tillage, as well as soils that naturally have high clay content and/or low organic matter content, will be more susceptible to damage from excessive pressing above the seed, especially when those soils are damp.
In no-till seeding, the wetter and more structured soils generally prevent press wheels on the soil surface from performing the seed-firming and furrow-closing functions adequately. The sidewall of the furrow formed in no-till seeding does not crumble easily like the sidewall in tilled conditions, where the soil had previously been loosened and fluffed by tillage. Accordingly, very high pressures are sometimes applied to the packing or closing wheels in an attempt to squeeze the furrow sidewalls back together. This typically results in poor seedling emergence because the soil in the furrow is more compressed at the surface compared to soil near the seed, sometimes to the extent of having a void immediately above the seed but with extremely compressed soil at the surface. In this instance, seed germination may fail due to the drying of air in the void, or the seedling may leaf underground in the void, or the seedling will encounter great difficulty pushing itself through the dense layer of soil, which will slow and weaken the seedling or even kill it.
Some improvements have been made by separating the seed firming and furrow closing functions. This is typically only possible where the depth-gauging function is already accomplished independently of the packing or closing wheel, as in the configuration where depth-gauging wheels travel alongside the furrow opening discs. Seeds are firmed into the soil in the bottom of the furrow by a narrow rolling wheel or sliding-type firmer exerting a relatively small amount of pressure onto the seed after it has been placed by the furrow opener disks and seed-directing tube.
Sliding seed-firming devices have a long history, appearing (but not described) in 1889 in Patric et al. '108, although as previously discussed, the device was not shaped nor positioned to function in the furrow or what remained of the furrow as the loose tilled soil sloughed back into the furrow after the opening disks had passed. The “presser-foot” is further depicted in Patric et al., U.S. Pat. No. 410,438, and in Packham, U.S. Pat. No. 530,962. More recent inventions have been true in-furrow sliding firmer devices, such as described in Keeton, U.S. Pat. Nos. 5,425,318 and 5,673,638, as well as Peterson et al., U.S. Pat. No. 6,119,608. Many of these sliding firming devices are hindered in their performance by mud or damp soil accumulation on the lower edges, especially if some soil disturbance occurs ahead of the firming device so that it no longer is operating in a ‘clean’ cut, or if insufficient pressure is applied to the sliding firming device. Soil accumulation on the underside of the firming device can result in dragging of seeds, and in a poor firming action. Sliding firming devices may also exhibit rapid wear in many soil conditions, unless made from exotic materials. Much of the problem derives from the compromise in making the entire sliding firmer out of a single material, such that it must be spring-like properties in its upper portion to create the pressure on the lower end that contacts the seed and soil, yet this lower end must be abrasion resistant for long wear life, and must be slick thereby resisting mud accumulation. Another aspect is that the spring-like properties of most UHMW materials degrades as a result of UV exposure, ground-level ozone, and moisture accumulation.
In attaching sliding firmers to double-disc opener planter designs commonly sold in North America in the past 30 years, the patents by Sauder et al., U.S. Pat. Nos. 6,918,342 B2 and 7,497,174 B2 are relevant in depicting and describing brackets that attach to the bolt or stud holding at least one of the opener disks, then extending rearward to hold a single-piece molded sliding firmer ‘tail’ in the correct position. Firmer brackets have also been attached to bolt holes in the opener subframe which exist in some planter models for holding the optional opener disk scrapers.